Check out example codes for "font awesome". It will help you in understanding the concepts better.

Code Example 1

<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.15.1/css/all.css" integrity="sha384-vp86vTRFVJgpjF9jiIGPEEqYqlDwgyBgEF109VFjmqGmIY/Y4HV4d3Gp2irVfcrp" crossorigin="anonymous">

Code Example 2

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous"> <!-- to use Font Awesome in html. This need to be in <head></head> tags to work -->
<body>
<i class="fa fa-linux" aria-hidden="true"></i>

Code Example 3

<p>Fixed Width:</p>
<div><i class="fas fa-arrows-alt-v fa-fw"></i> Icon 
   1</div>
<div><i class="fas fa-band-aid fa-fw"></i> Icon 
   2</div>
<div><i 
   class="fab fa-bluetooth-b fa-fw"></i> Icon 3</div>

<p>Without Fixed 
   Width:</p>
<div><i class="fas fa-arrows-alt-v"></i> Icon 1</div>
<div><i 
   class="fas fa-band-aid"></i> Icon 2</div>
<div><i class="fab fa-bluetooth-b"></i> Icon 
   3</div>

Code Example 4

Font Awesome is a font and icon toolkit based on CSS and Less.

It was made by Dave Gandy for use with Bootstrap, and later was incorporated
into the BootstrapCDN.

Font Awesome has a 38% market share among those websites that use third-party
font scripts on their platform, ranking it second place after Google Fonts.

Code Example 5

<link
      rel="stylesheet"
      href="https://use.fontawesome.com/releases/v5.13.0/css/all.css"
      integrity="sha384-Bfad6CLCknfcloXFOyFnlgtENryhrpZCe29RTifKEixXQZ38WheV+i/6YWSzkz3V"
      crossorigin="anonymous"
    />

Code Example 6

Make sure to put this just before the </body> tag!

<script src="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.13.0/js/all.min.js"></script>

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